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DESCRIPTION JPH1056684
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker device for sound reproduction.
[0002]
2. Description of the Related Art Various types of loudspeakers can be considered and put to
practical use as loudspeakers for sound reproduction.
[0003]
For example, a magnetic circuit having a gap between the center pole portion of the first
magnetic yoke and the plate is formed by sandwiching the magnet by the first magnetic yoke
called pole piece and the second magnetic yoke called plate. A speaker unit in which the primary
coil is fixed in the air gap of the magnetic circuit and fixed to the diaphragm so as to face it, and
the secondary coil is disposed in the air gap of the magnetic circuit; It has been put to practical
use.
[0004]
In this electromagnetically coupled speaker, the secondary current is induced in the secondary
coil by the signal current flowing through the primary coil, and the secondary coil is driven
according to the secondary current by the interaction with the magnetic flux generated in the air
gap of the magnetic circuit. A force is generated to vibrate the diaphragm to which the secondary
coil is fixed.
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[0005]
In this electromagnetically coupled speaker, the primary coil through which the signal current
flows is fixed to the first and / or second magnetic yokes made of a magnetic material such as
iron, so that it has the advantage of excellent heat dissipation and being able to withstand large
inputs. There is.
In addition, if the secondary coil is formed of a nonmagnetic conductive material such as
aluminum, and a short coil formed of a pipe or a cylinder forming a one-turn coil, distortion can
be reduced.
[0006]
On the other hand, a conductive type speaker in which a voice coil is disposed in the air gap of
the magnetic circuit has been put to practical use, and in this conductive type speaker, power is
supplied to the voice coil and unnecessary vibration is caused in the vibration system including
the voice coil. In order not to apply resistance, the voice coil is joined to a terminal provided on
the speaker frame by a lead wire made of a tinsel wire.
[0007]
In addition, the voice coil is divided into bits of digital audio signal by this conductive speaker,
and each coil is directly driven by data of each bit corresponding to each bit of digital audio
signal. Is considered.
[0008]
As described above, the electromagnetically coupled speaker has the advantages of being
excellent in heat dissipation and being able to withstand a large input, and also capable of
reducing distortion.
However, when the length of the air gap of the magnetic circuit is increased, the sensitivity of the
speaker is reduced, so the number of turns of the primary coil and the secondary coil can not be
increased.
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[0009]
Therefore, the inductance of the primary coil and the secondary coil can not be increased, and
the electromagnetic coupling force in which the secondary current is induced in the secondary
coil by the signal current flowing in the primary coil is as low as several kHz to 1 kHz or less It
becomes smaller in the region, and it is impossible to play up to 20 Hz, which is necessary for
playing audio.
Therefore, the electromagnetic coupling speaker is mainly used only as a speaker for highpitched sound reproduction.
[0010]
On the other hand, as described above, in the conductive speaker, the voice coil is joined to the
terminal provided on the speaker frame by the lead wire made of a tinsel wire.
In addition, it has been considered to divide the voice coil into the number of bits of the digital
audio signal and drive each coil directly with data of each bit of the digital audio signal using a
conductive speaker.
[0011]
However, at present, when digitizing an audio signal, it is common to set the digital audio signal
to 16 bits for faithful reproduction of the audio.
Therefore, in the case of driving a voice coil with a digital audio signal in a conductive type
speaker, 16 pairs of lead wires are required for one speaker.
[0012]
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However, since the tinsel wires, which are the lead wires, largely shake with the vibration of the
voice coil, the distance between them can not be reduced. Therefore, it is quite difficult to provide
as many as 16 pairs of tinsel cords in a small speaker.
[0013]
Therefore, the inventor of the present invention has proposed a novel speaker device capable of
reproducing up to the low frequency by driving the electromagnetic coupling speaker with a
digital signal.
[0014]
FIG. 16 shows a cross-sectional view of a structure of an example of an electromagnetic coupling
type speaker unit used for the novel speaker device.
[0015]
As shown in FIG. 16, the electromagnetic coupling type speaker unit of this example constitutes a
first yoke 1 provided with a cylindrical center pole portion 1a and a disk shaped flange portion
1b, and a second yoke. A magnetic circuit is formed by a doughnut-shaped plate 2, a doughnutshaped magnet 3 disposed between the flange portion 1b of the first yoke 1 and the plate 2, and
a magnetic gap GP between the plate 2 and the center pole portion 1a. Is configured.
[0016]
The flange portion 1b is provided with a magnet guide 15 having a step so that the center
positions of the magnet 3 and the center pole portion 1a coincide with each other.
Also, in assembling the magnetic circuit, a jig called a gap guide is used so that the center of the
center pole portion 1a coincides with the center of the plate 2, and the size of the magnetic gap
GP is equal to that of the center pole portion 21a. Between the outer circumferential surface of
the plate 22 and the inner circumferential surface of the plate 22.
[0017]
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Then, a drive coil as a primary coil is disposed on either or both of the outer peripheral surface
portion of the center pole portion 1a and the inner peripheral surface portion of the plate 2
facing each other across the magnetic gap GP.
In this embodiment, the primary coil 4 is disposed on the outer peripheral surface of the center
pole portion 1a.
In order to arrange the primary coil 4, a small diameter portion 1c having a length corresponding
to the winding width of the primary coil 4 is provided in the vicinity of the top of the center pole
portion 1a, and the primary coil 4 is provided on the small diameter portion 1c. Be
[0018]
In the case of this example, this primary coil 4 consists of a coil group of the number according
to the bit number of the input digital signal. For example, in the case of a binary code in which
the input digital signal is 16 bits / 1 sample and the most significant bit MSB is a sign bit
(positive or negative), the primary coil 24 excludes the MSB corresponding to the number of bits.
Fifteen coils are provided.
[0019]
And each of 15 coils is made into the number of turns according to the weight of each
corresponding bit. When the digital audio signal is linearly quantized, the number of turns of the
15 coils changes in a geometric progression corresponding to each bit from the least significant
bit LSB to the most significant bit MSB. It is assumed. For example, if the coil corresponding to
the LSB is 2 turns, the coil corresponding to 15 SB is 4 turns, the coil corresponding to 14 SB is 8
turns, the coil corresponding to 13 SB is 16 turns, and so on. It will be increased.
[0020]
The lead wire pair 17 derived from the primary coil 4 (in fact, there are 15 pairs, but only one
pair is shown in the figure for simplicity of explanation) is provided on the flange portion 1 b of
the first magnetic yoke 1. The through hole 14 is extended to the back side of the flange portion
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1b. Then, each of the lead wire pairs 17 is connected to 15 input terminals 18 (only one input
terminal is shown in the figure for simplicity of the description) provided on the back side of the
flange portion 1 b.
[0021]
In this case, in order to dissipate heat from the lead wire pair 17, the lead wire pair 17 is bonded
to the outer surface of the center pole portion 1 a and drawn out in the direction of the flange
portion 1 b of the first magnetic yoke 1.
[0022]
Then, a secondary coil 5C formed of a short coil electromagnetically coupled to the primary coil
4 is inserted into the gap GP.
In the case of this example, as shown in FIG. 17, the secondary coil units 5 constituting the
secondary coil 5C are respectively nonmagnetic and conductive materials such as aluminum are
formed in a cylindrical shape, It is considered to be a short coil of one turn. In this example, the
coil bobbin is omitted, and the secondary coil unit 5 is configured by only the short coil 5C. Of
course, a secondary coil unit can also be configured by winding a coil around a coil bobbin and
shorting the both ends.
[0023]
The secondary coil unit 5 configured as described above is attached to the speaker frame 11 via
the damper 10. In addition, a cone paper 9 as an example of a diaphragm is attached to and
attached to the secondary coil unit 5. The cone paper 9 is attached to the speaker frame 11 by
the gasket 12 through the flexible edge 9 e. Finally, the cap 13 is adhesively attached to the top
edge of the cone 9 or secondary coil unit 5.
[0024]
If signal input according to each bit of the digital signal is respectively added to the input
terminals 18 of the number corresponding to the number of bits of the electromagnetically
coupled speaker described above, the current flowing in each of the plurality of coils constituting
the primary coil 4 Accordingly, a current is induced in the short coil as the secondary coil 5C,
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and the interaction with the magnetic flux in the air gap GP causes the secondary coil unit 5 to
vibrate up and down according to Fleming's left-hand rule.
[0025]
In this case, the sampling frequency when digitizing the audio signal is a frequency such as 44.1
kHz or 48 kHz, which is twice as high as 20 kHz which is said to be the upper limit of the audio
frequency.
Therefore, low frequency components such as several kHz to 1 kHz or less of the voice signal
before being digitized are also high frequencies exceeding 20 kHz as the digital voice signal.
[0026]
In addition, the electromagnetic coupling speaker reduces the length of the air gap of the
magnetic circuit so that the speaker sensitivity does not decrease, and the signal flowing in the
primary coil even if the number of turns of the primary coil and the secondary coil is reduced.
When the frequency of the current is such a high frequency that exceeds 20 kHz, the
electromagnetic coupling force does not decrease, and sound can be reproduced.
[0027]
Then, in the speaker device of the present invention configured as described above, since the
primary coil of the electromagnetic coupling speaker is driven by the digital audio signal, the low
frequency component of the audio signal before being digitized is also The signal current flowing
through the primary coil has a high frequency exceeding 20 kHz.
Therefore, the electromagnetic coupling speaker enables reproduction up to the low frequency
range.
[0028]
Like general speakers, the vibration system of the speaker unit is not sensitive to high
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frequencies, and in particular, hardly reproduces high frequency components such as 20 kHz or
more. Therefore, even if the plurality of coils of the primary coil are driven by the digital signal of
the sampling frequency of 44.1 kHz or 48 kHz, the sampling frequency component is hardly
reproduced. Even if the sound is reproduced with a very small sound pressure, sounds over 20
kHz can hardly be heard by the human ear, so no problems occur even when listening to music.
[0029]
In addition, it is also easy to intentionally form a mechanical filter having a stop band of 20 kHz
or more and incorporate it into the speaker unit.
[0030]
In addition, it is possible to realize a speaker apparatus with small distortion and a large
maximum output, which reproduces the audio directly by the digital audio signal without using
the D / A converter and the power amplifier.
[0031]
By the way, in this electromagnetic coupling speaker, mid-high range sound is emitted from the
central portion of the cone paper 9 and the portion of the cap 13.
For this reason, the secondary coil unit 5 and the cone paper 9 and the cap 13 need to be firmly
adhered and fixed in order to vibrate in the middle and high regions.
[0032]
However, since the cone paper 9 and the cap 13 and aluminum, which is the secondary coil unit,
are bonded by an adhesive such as an epoxy agent, the strength is weak compared to the
integrated product, and hence the middle and high frequency characteristics are There is a
possibility that the sound quality of the mid-high range may deteriorate.
[0033]
In view of the above, the present invention has an object to provide a speaker apparatus using
the above-described novel electromagnetically coupled speaker unit, which can improve the
middle to high band characteristics and the middle to high band sound quality. Do.
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[0034]
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to
the present invention, a primary coil fixed in the vicinity of an air gap in a magnetic circuit, and
the primary coil disposed in the air gap, It is attached to a secondary coil composed of a short
coil in which a secondary current is induced according to the current flowing in the coil, and a
coil bobbin of a secondary coil unit in which the secondary coil is formed, and a speaker via an
edge portion A speaker unit comprising a main diaphragm fixed to a frame and an auxiliary
diaphragm attached to the secondary coil as an integral part, and a speaker drive circuit for
driving the primary coil of the speaker unit by a digital audio signal And
[0035]
The secondary coil has a cylindrical shape made of a nonmagnetic material and a conductive
material, and the coil bobbin is omitted to constitute a secondary coil unit, and the subdiaphragm is integrated with the cylindrical secondary coil. It is good to form as a part.
[0036]
According to this invention of the above configuration, the sound of the middle and high
frequencies is reproduced by the sub diaphragm formed as an integral part of the secondary coil
unit.
Therefore, the middle to high frequency characteristic is improved, and the sound quality of the
middle to high frequency becomes good.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a speaker device
according to the present invention will be described below with reference to the drawings.
[0038]
FIG. 1 shows a cross-sectional view of a structure of an embodiment of a speaker unit used for a
speaker device according to the present invention.
[0039]
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As shown in FIG. 1, the speaker unit of this example is an electromagnetically coupled speaker,
and the structure of the portion of the secondary coil unit is different from that of the speaker
unit of the example of FIG. Is almost the same.
[0040]
That is, in the speaker unit of this example, the first yoke 21 including the cylindrical center pole
portion 21a and the disk-shaped flange portion 21b, the toroidal plate 22 constituting the second
yoke, and A magnetic circuit is constituted by a doughnut-shaped magnet 23 disposed between
the flange portion 21 b of the yoke 21 and the plate 22 and a magnetic gap GP between the plate
22 and the center pole portion 21 a.
[0041]
The flange portion 21b is provided with a magnet guide 35 having a step so that the center
positions of the magnet 23 and the center pole portion 21a coincide with each other.
[0042]
Then, a drive coil as a primary coil is disposed on either or both of the outer peripheral surface
portion of the center pole portion 21a and the inner peripheral surface portion of the plate 22
facing each other across the magnetic gap GP.
In this embodiment, the primary coil 24 is disposed on the outer peripheral surface of the center
pole portion 21a, as in the above-described example.
In order to dispose the primary coil 24, a small diameter portion 21c having a length equivalent
to the winding width of the primary coil 24 is provided in the vicinity of the top of the center
pole portion 21a, and the primary coil 24 is fixed to the small diameter portion 21c. Be done.
[0043]
Also in this example, the primary coil 24 is composed of a coil group whose number corresponds
to the number of bits of the input digital signal, and as described above, for example, the input
digital signal is 16 bits / 1 sample, and the highest order In the case of a 2'-complement code in
which the bit MSB is a sign bit (positive or negative), for example, 15 coils are provided as the
primary coil 24 corresponding to the number of bits.
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[0044]
And each of 15 coils is made into the number of turns according to the weight of each
corresponding bit.
When the digital audio signal is linearly quantized, the number of turns of the 15 coils changes in
a geometric progression corresponding to each bit from the least significant bit LSB to the most
significant bit MSB. It is assumed.
[0045]
When the analog voice signal is nonlinearly quantized and converted to a digital voice signal, the
number of turns of the plurality of coils constituting the primary coil 24 changes in the
geometric progression as described above. Instead of changing it, it should be changed according
to the non-linear characteristic of the non-linear quantization.
[0046]
An example of the primary coil 24 is shown in FIG. 2A.
This example is a case where the primary coil 24 is configured as an air core coil.
That is, as shown in FIG. 2A, the primary coil 24 consists of 15 coils LA to LG, LI to LP each
having a different number of turns, and from each coil LA to LG, LI to LP, the winding start and
winding thereof The final lead pairs 37a-37g, 37i-37p are derived.
Then, the primary coil 24 is inserted into the small diameter portion 21c of the center pole
portion 21a shown in FIG. 2B, adhered, and fixed in the state as shown in FIG.
[0047]
The primary coil 24 may be a wire wound around a bobbin 36 of a magnetic material as shown
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in FIG. 3A, or as shown in FIG. 3B, the small diameter portion 21c of the center pole portion 21a.
The wire may be directly wound and attached.
[0048]
Fifteen lead wire pairs 37a to 37p derived from the primary coil 24 pass through one or more
through holes 34 provided in the flange portion 21b of the first magnetic yoke 21 to form the
flange portion 21b. It is extended to the back side.
Each of these lead wire pairs 37a to 37p (only one pair is described as a representative number
37 in FIG. 1) has 15 input terminals 38a to 38p (represented in FIG. 1) provided on the back side
of the flange portion 21b. Only one is described as 38 as a number).
[0049]
In this case, the lead wire pairs 37a to 37p are bonded to the outer surface of the center pole
portion 21a and dissipated in the direction of the flange portion 21b of the first magnetic yoke
21 for heat dissipation from the lead wire pairs 37a to 37p. Ru.
As shown in FIG. 3B, instead of bonding, for example, paper 39 is wound from above the lead
wire pair of the center pole portion 21a, and this paper 39 causes the lead wire pair to contact
the center pole portion 21a side. You may make it press.
[0050]
And in this embodiment, the secondary coil 25C which consists of a short coil
electromagnetically coupled with the primary coil 24 is inserted into the air gap GP.
In the case of this example, the secondary coil 25C is formed as the secondary coil unit 25 itself.
The secondary coil unit 25 may be configured by inserting a secondary coil consisting of a
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cylindrical ring into a coil bobbin, or by connecting both ends and shorting a coil by winding
around the coil bobbin, but this embodiment In the same manner as in the above-described
example, as shown in FIG. 4, a nonmagnetic and conductive material such as aluminum is
cylindrically formed to form a one-turn short coil. By the coil 25C, the coil bobbin is omitted, and
the secondary coil unit 25 is configured.
[0051]
Then, as shown in FIG. 4, the auxiliary diaphragm 26 is formed integrally with the secondary coil
unit 25.
The auxiliary diaphragm 26 is mainly for reproduction radiation of middle to high frequency
sound, and has a shape of a sagger having a predetermined inclination.
The integrated component 27 composed of the secondary coil unit 25 and the auxiliary
diaphragm 26 forms, for example, a portion of the auxiliary diaphragm 26 by performing a
processing process called shrinkage reduction on a cylindrical aluminum ring. It is molded
by
[0052]
The auxiliary bobbin 28 or the secondary coil 25C is fixed and disposed on the outer peripheral
portion of the secondary coil unit 25 above the magnetic gap GP of the integrated component 27
having the above-described configuration. Then, the auxiliary bobbin 28 or the secondary coil
25C is attached to the speaker frame 31 via the damper 30, so that the component 27 composed
of the secondary coil unit 25 and the auxiliary diaphragm 26 is attached.
[0053]
In addition, cone paper 29 as an example of the main diaphragm is attached to the auxiliary
bobbin 28 or the secondary coil 25C. The cone paper 29 is attached to the speaker frame 31 by
the gasket 32 through the flexible edge 29e.
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[0054]
For example, as shown in FIG. 5A, the auxiliary bobbin 28 is configured by winding a reinforcing
paper 28P around a bobbin 28B in which rectangular plates are abutted and made annular. The
inner diameter of the bobbin 28 B is set to be substantially equal to the outer diameter of the
secondary coil unit 25. A state in which the predetermined position of the secondary coil unit of
the component 27 is adhesively fixed to the auxiliary bobbin 28 in the example of FIG.
[0055]
In addition, as the auxiliary bobbin 28, one configured by a spiral bobbin 28S as shown in FIG.
5B can also be used.
[0056]
A method of assembling the speaker unit having the above configuration will be described below.
[0057]
As shown in FIG. 2B, the primary coil 24 is inserted into the portion of the small diameter portion
21c above the center pole portion 21a and adhered.
[0058]
Next, the lead wire pairs 37a to 37g and 37i to 37p from the 15 coils LA to LA, LI to LP
constituting the primary coil 24 are pulled out to the back side of the yoke 21 through the
through holes 34, and the input terminal Solder and fix to 38a-38g and 38i-38p.
The lead wire portion in contact with the center pole portion 21a is bonded to the center pole
portion 21a for the purpose of heat radiation.
The above fixing of the primary coil 24 is performed in the process prior to the assembly of the
magnetic circuit.
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[0059]
Next, an adhesive is applied to the front surface of the flange portion 21b of the yoke 21 and the
magnet 23 is placed, and the inner diameter of the magnet 23 and the outer diameter of the
magnet guide 35 formed as a step on the front surface of the flange portion 21 The center pole
portion 21a and the magnet 23 are aligned so that the centers of the center pole portion 21a and
the magnet 23 substantially coincide with each other.
[0060]
Next, an adhesive is applied to the upper surface of the magnet 23 and the plate 22 is placed.
Then, a jig called a gap guide is inserted so that the inner diameter of the plate 22 and the outer
diameter of the center pole portion 21a are concentric.
[0061]
The speaker frame 31 is attached to the plate 22 in advance by means such as caulking.
Alternatively, after completing the magnetic circuit, the speaker frame 31 may be attached to the
plate 22 by means such as a screw.
[0062]
After the adhesive between the plate 22 and the magnet 23 is dried, the gap guide is pulled out
of the center pole portion 21a. The body of the speaker is now complete.
[0063]
Next, a jig called an auxiliary bobbin 28 or a secondary coil 25C and a coil spacer is prepared.
The coil spacer is a jig whose outer diameter is matched to the inner diameter of the auxiliary
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bobbin 28 or the secondary coil 25C, and whose inner diameter is matched to the outer diameter
of the center pole portion 21a.
[0064]
Then, insert this coil spacer inside the auxiliary bobbin 28 or secondary coil 25C and align the
coil spacer so that the auxiliary bobbin 28 or secondary coil 25C comes to a predetermined
position above the gap GP. Insert it into the center pole 21a.
[0065]
Next, as it is, the outer peripheral part of the damper 30 is adhered to the speaker frame 31, and
the inner peripheral part of the damper 30 is bonded and fixed to the outer peripheral part of the
auxiliary bobbin 28, so that the secondary coil unit 25 has a center pole part. It is made to move
freely in the axial direction of 21a.
[0066]
Next, the outer peripheral portion of the cone paper (main diaphragm) 29 with the edge 29 e is
adhered and fixed to the outer peripheral portion of the speaker frame 31 via the gasket 32.
Further, the inner peripheral portion of the cone paper 29 is adhered and fixed to the outer
peripheral portion of the auxiliary bobbin 28 or the secondary coil 25C.
Then, after the adhesive is dried, the coil spacer is pulled out from the center pole portion 21a.
[0067]
When the damper 30 and the cone paper 29 are attached to the secondary coil 25C, the cap 33
is adhered near the top of the auxiliary diaphragm 26, and the magnet 23 is magnetized to
complete the speaker device.
[0068]
Next, the part of the secondary coil unit 25 of the integrated component 27 of the secondary coil
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unit 25 and the auxiliary diaphragm 26 shown in FIG. 4 is inserted into the inner peripheral side
of the auxiliary bobbin 28, and the secondary coil After positioning so that 25C is at a
predetermined position in the magnetic gap GP, adhesive fixing is performed.
At this time, a coil spacer different from the above is prepared, and it is inserted between the
secondary coil unit 25 and the center pole portion 21a.
[0069]
After the adhesive between the auxiliary bobbin 28 and the component 27 is dried, the coil
spacer is pulled out of the center pole portion 21a.
[0070]
Then, the cap 33 is adhered in the vicinity of the top of the auxiliary diaphragm 26.
After the adhesive is dried, the magnet 23 is magnetized to complete the speaker device.
[0071]
If a signal input corresponding to each bit of the digital signal is added to the input terminals 38a
to 38g and 38i to 38p of the electromagnetic coupling type speaker unit described above, the
secondary coil 25C is generated according to the current flowing through the primary coil 24.
The current is induced, and the interaction with the magnetic flux in the air gap GP causes the
secondary coil unit 25 to vibrate up and down according to Fleming's left-hand rule. In this case,
the change period of the digital signal is 44.1 kHz or 48 kHz, which is its sampling frequency,
and the inductive coupling force between the secondary coil 25C and the primary coil 24 does
not decrease, and Reproduction is possible.
[0072]
Then, in the electromagnetic coupling type speaker unit of this example, the secondary coil 25C
(secondary coil unit 25) is formed in a cylindrical shape of aluminum, and a sub-vibration plate
26 for middle and high sound is integrally provided therewith. Because of this, the Young's
modulus of the junction between the secondary coil unit 25 and the auxiliary diaphragm 26 is
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very large compared to adhesion, and the rigidity is high, so that the deterioration of the midhigh frequency characteristics and the mid-high frequency sound quality is small.
[0073]
That is, there is a possibility that the mid-high frequency characteristic and the mid-high
frequency sound quality may be deteriorated because the Young's modulus of the bonding
portion between the cone paper 29 which is the main diaphragm and the secondary coil unit 25
is small. In the above, the presence of the auxiliary diaphragm 26 provided integrally with the
secondary coil unit 25 improves the mid-to-high range characteristic and the sound quality of the
mid-to-high range.
[0074]
Although the above-described embodiment is an example in which the secondary coil unit is
constituted only by the secondary coil consisting of a cylindrical short coil, the cylindrical short
coil is inserted in the bobbin or the short coil is wound in the bobbin It may be something.
In that case, the secondary diaphragm is provided as an integral part with the bobbin of the
secondary coil unit.
[0075]
In this specification, integral is not limited to the case of processing an integral body like a
squeezer, but also welding, welding, etc. in which Young's modulus at a joint portion is 10 times
or more larger than adhesion. It includes those which are joined and integrated by a joining
method of the above into one part.
[0076]
Next, an example of an audio reproduction system using a speaker unit according to the present
invention is shown in FIG.
The example of FIG. 7 is a case where the voice is reproduced by the digital voice signal from the
digital voice output device.
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[0077]
The digital audio output device 210 is a CD player or DAT (digital audio tape recorder) or the
like, from its digital output terminal, for example, from the left and right channel audio signals
digitized to 16 bits at a sampling frequency of 44.1 kHz or 48 kHz. The stereo audio signal is
output as serial data alternately for every one sample of left and right audio data.
[0078]
The 16-bit digital audio signal of serial data from the digital audio output device 210 is supplied
to the serial-to-parallel converter 220, and the serial-to-parallel converter 220 separates the
digital audio signals of the left and right channels. The 16-bit left and right digital audio signals
converted into parallel data and converted into parallel data are supplied to the left and right
channel speaker devices 100L and 100R.
[0079]
Although not shown, in the serial-to-parallel converter 220, a clock of a bit rate is obtained, and
the clock of this bit rate is supplied to the decoder 70.
[0080]
The speaker devices 100L and 100R each include a decoder 70, a speaker drive circuit 40, and a
speaker unit 110 in this example.
The speaker unit 110 is configured of the electromagnetic coupling type speaker unit described
using FIGS. 1 to 4 described above.
[0081]
Then, in the case of this example, in the speaker devices 100L and 100R, in the decoder 70,
control signals as will be described later are generated from the 16-bit left and right digital audio
signals converted to parallel data from the serial to parallel converter 220. The generated control
signal is supplied to the speaker drive circuit 40, and the speaker drive circuit 40 drives the
primary coil 24 of the speaker unit 110.
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[0082]
When the primary coil 24 is composed of a plurality of coils, when the 16 bit digital audio signal
is a 2 'complement code as shown in FIG. 8, its MSB (most significant bit) is used as a sign bit, As
described above, and as shown in FIGS. 8 and 9, the primary coil 24 is composed of 15 coils LA
to LG and LO to LP.
Then, the coil LA is made to correspond to the LSB (least significant bit), for example, 2 turns,
and the coils LB, LC, LD, LE, LF, LG, LI, LJ, LK, LL, LM, LN, LO, 4 LPs, 8 turns, 16 turns ...
corresponding to 15SB, 14SB, 13SB, 12SB, 11SB, 10SB, 9SB, 8SB, 7SB, 6SB, 4SB, 3SB, 2SB,
respectively. The number of turns is twice the number of turns of the coil corresponding to the
three lower bits.
[0083]
When the analog voice signal is nonlinearly quantized and converted to a digital voice signal, the
number of turns of the plurality of coils constituting the primary coil 24 changes in the
geometric progression as described above. Instead, it changes according to the non-linear
characteristic of the non-linear quantization.
[0084]
FIG. 10 shows an example of the part of the decoder 70 and the speaker drive circuit 40 shown
in FIG. 7. The speaker drive circuit 40 corresponds to the 15 coils LA to LG and LI to LP of the
primary coil 24. The coil drive circuits 40A to 40G and 40I to 40P are provided.
[0085]
In each of the coil drive circuits 40A to 40G and 40I to 40P, four FETs 51 to 54 as switching
elements and corresponding ones of the coils LA to LG and LI to LP of the primary coil 24 are
provided. A circuit configured by bridge connection and a constant current source 41 are
connected in series.
[0086]
Then, when the FETs 51 and 53 are turned on and the FETs 52 and 54 are turned off, the current
Ia of the constant current source 41 corresponds to a coil corresponding to each bit among the
plurality of coils of the primary coil (hereinafter When the FETs 51 and 53 are turned off and the
FETs 52 and 54 are turned on, the current Ia of the constant current source 41 is caused to flow
11-05-2019
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in the negative direction to the corresponding primary coil.
[0087]
The currents of the constant current sources 41 of the coil drive circuits 40A to 40G and 40I to
40P are all made equal as indicated by the current Ia.
In the same coil drive circuit, when all the FETs 51 to 54 are turned on or off, no current flows in
the corresponding primary coil.
[0088]
The decoder 70 corresponds to the 15 coils LA to LG and LI to LP of the primary coil 24, that is,
15 control signal generation circuits 70A to 70G corresponding to 15 bits excluding the MSB of
the digital audio signal. , 70I to 70P, and from the respective control signal generation circuits
70A to 70G and 70I to 70P, the MSBs of the digital audio signal converted into parallel data from
the serial to parallel converter 220 and the respective control signal generation circuits 70A 70
control signals G1 to G4 to be described later are obtained respectively from lower bits (LSB to
2SB) corresponding to 70G and 70I to 70P, and the control signals G1 to G4 correspond to the
speaker drive circuit 40. Are supplied to the gates of the FETs 51 to 54 of the coil drive circuit.
[0089]
The four control signals G1 to G4 are levels at which the control signals G1 and G3 turn on the
FETs 51 and 53 when the MSB of the input digital audio signal is 0 and the corresponding lower
bit is 1, and the control signals G2 and G4 are At the level at which the FETs 52 and 54 are
turned off, the current Ia flows in the positive direction to the corresponding primary coil.
On the other hand, when the MSB of the digital audio signal is 1 and the corresponding lower bit
is 0, the control signals G1 and G3 turn off the FETs 51 and 53, and the control signals G2 and
G4 turn on the FETs 52 and 54. A current Ia flows through the corresponding primary coil in the
negative direction opposite to the above.
[0090]
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21
Also, when the MSB of the digital audio signal is 0 and the corresponding lower bit is also 0, or
when the MSB is 1 and the corresponding lower bit is also 1, the control signals G1 to G4 turn off
the FETs 51 to 54. And no current flows in the corresponding primary coil.
[0091]
When all the control signals G1 to G4 turn on the FETs 51 to 54, it is possible to prevent current
from flowing to the corresponding primary coil.
In that case, a current always flows in the circuit, and a stable operation can be performed.
[0092]
The driving force F of the vibration system of the electromagnetic coupling speaker is the
secondary current i induced in the secondary coil, the density B of the magnetic flux generated in
the air gap of the magnetic circuit, and the length of the secondary coil in the air gap of the
magnetic circuit Since the magnetic flux density B and the length L are constant as F = B · L · i as
the product with L, the driving force F of the vibration system is the secondary current i induced
in the secondary coil It will be proportional.
The secondary current i induced in the secondary coil 25 is proportional to the product of the
signal current flowing through the primary coil and the number of turns of the primary coil.
[0093]
Then, in the above-described example, the number of turns of each of the coils LA to LG and LI to
LP of the primary coil 24 is set to the number of turns proportional to the weight of each bit
excluding the MSB of the input digital audio signal. Among the 15 coils of the next coil 24,
corresponding to the coil through which the current Ia flows as the signal current, the secondary
coil 25C receives the primary coil 24 in the direction according to the value of the MSB of the
digital audio signal. The secondary current of the current value proportional to the weight of the
bit corresponding to the coil through which the current Ia flows is induced.
[0094]
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22
That is, in the secondary coil 25C, a secondary current of the sum of current values proportional
to the weight of the bit corresponding to the coil through which the current Ia of the primary coil
24 flows.
Thereby, the cone paper 29, which is a diaphragm to which the secondary coil unit 25 is fixed,
vibrates in the direction according to the value of the MSB of the input digital audio signal by an
amount proportional to the digital data value of the one sample. The speaker unit 110
reproduces the audio faithful to the input digital audio signal.
[0095]
The switching elements of the coil driving circuits 40A to 40G and 40I to 40P are not limited to
FETs, and other elements operating at high speed can be used.
[0096]
In the example described above, the number of turns of each of the coils LA to LG and LI to LP
constituting the primary coil 24 is the number of turns proportional to the weight of each bit
excluding the MSB of the input digital audio signal. In the case of reproducing the difference in
weight of each bit of the audio signal, the number of turns of each of the coils LA to LG and LI to
LP is the same, and the coil drive circuits 40A to 40G and 40I to 40P corresponding thereto are
provided. By changing the current value of the constant current source, the difference in weight
of each bit of the input digital audio signal can also be reproduced.
[0097]
FIG. 11 shows an example in this case, and the 15 coils LA to LG and LI to LP constituting the
primary coil 24 are all made to have the same number of turns, for example, 50 turns, and the
coils LA to LG, The currents Ia to Ig and Ii to Ip of the constant current sources 4LA to 41G and
41I to 41P of the coil drive circuits 40A to 40G and 40I to 40P corresponding to LI to LP are
changed as described later.
Others are the same as the example of FIG.
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23
[0098]
As described above, the driving force F of the vibration system of the speaker unit 110 is
proportional to the secondary current i induced in the secondary coil, and the secondary current
i is the signal current flowing through the primary coil and the primary coil It is proportional to
the product of the number of turns.
[0099]
Therefore, in this example, although not shown in FIG. 11, the current Ib of the constant current
source of the coil drive circuit corresponding to the coil LB corresponding to 15SB of the digital
audio signal as shown in FIGS. The current Ia of the constant current source 41A of the coil drive
circuit 40A corresponding to the coil LA corresponding to the LSB of the digital audio signal is
doubled.
すなわち、Ｉｂ＝２Ｉａとされる。
[0100]
The currents Ic, Id, Ie,... Of the constant current source of the coil drive circuit corresponding to
the coils LC, LD, LE... Corresponding to the digital audio signals 14SB, 13SB, 12SB,. , ... doubled.
[0101]
Therefore, as in the example of FIG. 10, in the speaker unit 110, the diaphragm 29 is
proportional to the weight of the bit corresponding to the primary coil through which the signal
current flows in the direction corresponding to the value of the MSB of the digital audio signal. It
vibrates and the audio is reproduced faithfully to the input digital audio signal.
[0102]
When the difference in weight of each bit of the digital audio signal is reproduced by changing
the current value of the constant current source as described above, one drive coil can be used as
the primary coil.
The primary coil in this case is attached to either the center pole portion 21 a or the plate 22.
11-05-2019
24
[0103]
FIG. 12 shows an example in that case.
However, this example is a case where the input digital audio signal, that is, the 16-bit digital
audio signal converted into parallel data from the serial-to-parallel converter 220 is a natural
binary code.
[0104]
In this example, the primary coil 111 is formed of one coil, and constant current sources 61A,
61B,... Of currents Ia, Ib,. , 61P are respectively connected via switch circuits 62A, 62B,..., 62P,
and switch circuits 62A, 62B,..., 62P are switched by data of corresponding bits of the digital
audio signal from serial to parallel converter 220. .
[0105]
That is, when a certain bit of the input digital audio signal is 1, the corresponding switch circuit
is turned on, and the current of the corresponding constant current source flows through the
primary coil 111.
The current Ib of the constant current source 61B is twice as high as the current Ia of the
constant current source 61A, and the current of the constant current source corresponding to
each bit of the digital audio signal corresponds to one lower bit hereinafter. It is twice the current
of the constant current source.
[0106]
Therefore, in this example, in the speaker unit 110, the diaphragm 29 vibrates in one direction
by an amount proportional to the weight of each bit of the input digital audio signal, and the
audio is reproduced faithfully to the input digital audio signal.
[0107]
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25
The primary coil 111 is not one, and two or more coils having the same number of turns are
provided, the current corresponding to each bit of 16 bits is divided into the corresponding
number of groups, and the current of each group is one coil It can also be configured to flow
against.
For example, a primary coil is constituted by one coil provided in the center pole portion 21a and
one coil provided in the plate 22, while the digital signal is divided into upper 8 bits and lower 8
bits. And a group of current corresponding to each of the two coils may be made to flow.
[0108]
Even when the input digital audio signal is a 2 'complement code, coil drive circuits 40A to 40P
as shown in FIG. 11 are switched by data of corresponding bits of the digital audio signal. , And
the primary coil 111 can be one.
[0109]
Furthermore, by combining the difference in the number of turns of the plurality of primary coils
with the difference in the current value of the plurality of constant current sources, it is possible
to reproduce the difference in weight of each bit of the digital audio signal.
[0110]
FIG. 13 shows an example in that case.
However, this example is a case where the input digital audio signal, that is, the 16-bit digital
audio signal converted into parallel data from the serial-to-parallel converter 220 is a natural
binary code.
[0111]
In this example, the primary coil is composed of four coils 111S, 111T, 111U, and 111V with a
turn ratio as described later, and drive blocks S, T, and T for the respective coils 111S, 111T,
111U, and 111V. U and V are provided, and constant current sources of currents Ia, Ib, Ic and Id
respectively correspond to corresponding coils 111 S, 111 T, and 111 T via switching circuits. It
11-05-2019
26
is connected to 111U or 111V.
[0112]
That is, in drive block S, constant current sources 61A, 61B, 61C, 61D are connected to
corresponding coils 111S via switch circuits 62A, 62B, 62C, 62D, respectively, and in drive block
T, constant current source 61E. , 61F, 61G, 61H are connected to corresponding coils 111T via
switch circuits 62E, 62F, 62G, 62H, respectively, and in the drive block U, constant current
sources 61I, 61J, 61K, 61L are switch circuits respectively. 62I, 62J, 62K, and 62L are connected
to the corresponding coil 111U, and in the drive block V, constant current sources 61M, 61N,
61O, and 61P are connected via switch circuits 62M, 62N, 62O, and 62P, respectively. The
switch circuit 62A, 6 is configured to be connected to the corresponding coil 111V. B ... 62N,
62O, 62P is switched by the corresponding bit data of the input digital audio signal.
[0113]
The turn number ratio of the coils 111S, 111T, 111U and 111V is 1: 16: 162: 163.
The ratio of the currents Ia, Ib, Ic, Id of the constant current sources 61A, 61B, 61C, 61D is 1: 2:
22: 23.
すなわち、Ｉｂ＝２・Ｉａ，Ｉｃ＝２2 ・Ｉａ，Ｉｄ＝２3 ・Ｉａ
[0114]
As described above, the driving force F of the vibration system of the speaker unit 110 is
proportional to the secondary current i induced in the secondary coil, and the secondary current
i is the signal current flowing through the primary coil. It is proportional to the product of the
number of turns of the primary coil.
[0115]
Therefore, in this example, when a certain bit of the digital audio signal becomes 1, the
corresponding ones of the switch circuits 62A, 62B... 62P are turned on, and the current flows to
the primary coil 111S, 111T, 111U or 111V. With the flow of Ia, Ib, Ic or Id, the ratio of the
secondary current induced in the secondary coil corresponds to the ratio of the weight of each
bit of the digital audio signal.
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27
[0116]
Therefore, as in the example of FIG. 12, in the speaker unit 110, the diaphragm 29 is shifted in
one direction by an amount proportional to the weight of each bit of the digital audio signal, and
the audio is reproduced faithfully to the input digital audio signal. Be done.
[0117]
And in this example, the ratio of the number of turns between the primary coil 111S of the
minimum number of turns and the primary coil 111V of the maximum number of turns can be
reduced to 1: 163 = 1: 212. In addition, the ratio of the current value between the minimum
current value Ia and the maximum current value Id can be significantly reduced to 1:23.
[0118]
Although not shown, the primary coil is composed of four coils with a ratio of the number of
turns of 1: 2: 4: 8, and the current value of each coil via the switch circuit is not shown. The four
constant current sources with the ratio of 1: 16: 162: 163 are connected, and the combination of
the four constant current sources with the smallest current value and each coil can be used as
the LSB and 2SB of the input digital audio signal, respectively. , 3SB and 4SB corresponding to
the input digital audio signals 5SB, 6SB, 7SB and 8SB, respectively, with the combination of four
constant current sources with the second smallest current value and respective coils
corresponding to The combinations of the four largest constant current sources and each coil
correspond to the input digital audio signals 9SB, 10SB, 11SB and 12SB, respectively, and the
four constant current sources having the largest current value and each coil set The combination
may be made to correspond to the digital voice signals 13SB, 14SB, 15SB and MSB, respectively.
According to this, between the minimum number of turns of the primary coil and the maximum
number of turns of the primary coil The ratio of the number of turns of the current can be
significantly reduced to 1: 8 and the ratio of the current value between the minimum current
value to the maximum current value is significantly reduced to 1: 163. Can.
[0119]
In this way, it is possible to reproduce from bass to treble with flat frequency characteristics, and
to reproduce audio directly from digital audio signals without using a D / A converter or a power
amplifier. Low distortion, maximum output A large speaker device can be realized.
[0120]
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28
FIG. 14 shows another example of the speaker device of the present invention.
In this example, an analog audio signal Ao from an analog audio output device 510 such as a
cassette player or an FM tuner is supplied to a chopper circuit 520, and an audio signal is audible
in the chopper circuit 520 as shown by an analog audio signal Ac in FIG. It is chopped at a
frequency fc higher than the frequency, that is, a frequency fc exceeding 20 kHz which is said to
be the upper limit of the audio frequency.
[0121]
However, it is desirable that the chopping frequency fc be a high frequency around twice 20 kHz,
for example, 40 kHz.
In addition, the time width of the chopping period is sufficiently shorter than the chopping
period Tc.
[0122]
Then, the chopped analog audio signal Ac from the chopper circuit 520 is amplified by the power
amplifier 530 and supplied to the primary coil 111 of the speaker unit 110 described above.
In this case, the speaker unit 110 has one primary coil 111.
As a result of the audio signal current being supplied to the primary coil 111, a secondary
current is induced in the secondary coil, and the diaphragm vibrates.
[0123]
As described above, the speaker unit 110, which is an electromagnetic coupling speaker, has a
low frequency of several kilohertz to 1 kilohertz or less where the secondary current i is induced
in the secondary coil by the signal current flowing through the primary coil 111. It becomes
small.
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29
[0124]
However, according to the example of FIG. 14, since the analog audio signal is interrupted at a
frequency fc higher than the audio frequency and supplied to the primary coil 111 of the speaker
unit 110, the low frequency component of the analog audio signal is also 1 The signal current
flowing to the next coil 111 has a high frequency exceeding 20 kHz.
Therefore, the frequency characteristic from the low band to the high band is flat by the speaker
unit 110 which is an electromagnetic coupling speaker, and good reproduction of the sound
quality becomes possible.
[0125]
As described above, according to the present invention, the sub-diaphragm for medium and high
frequency range reproduction is integrally provided in the secondary coil unit of the
electromagnetically coupled type speaker unit which is digitally driven. Improve the sound
quality of middle and high range characteristics and middle and high range.
[0126]
Brief description of the drawings
[0127]
1 is a cross-sectional view of the structure of an example of a speaker unit used in an
embodiment of a speaker device according to the present invention.
[0128]
2 is a diagram showing an example of a primary coil used in the speaker unit of FIG.
[0129]
3 is a diagram showing another example of the primary coil used in the speaker unit of FIG.
[0130]
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30
4 is a diagram showing an example of an integrated component of the secondary coil and the
auxiliary diaphragm used in the speaker unit of FIG.
[0131]
5 is a diagram showing an example of the auxiliary bobbin used in the speaker unit of FIG.
[0132]
6 is a view showing a state in which the integrated component of FIG. 4 is attached to the
auxiliary bobbin of the example of FIG.
[0133]
7 is a diagram showing an example of an audio reproduction system using an example of the
speaker device according to the present invention.
[0134]
8 is a diagram for explaining the input digital signal.
[0135]
<Figure 9> It is the figure in order to explain the drive principle of the speaker device due to this
invention.
[0136]
10 is a circuit diagram showing a specific example of a partial circuit of FIG.
[0137]
<Figure 11> It is the figure which shows one example of the audio playback system which uses
the other example of the speaker device due to this invention.
[0138]
12 is a diagram showing an example of an audio reproduction system using another example of
the speaker apparatus according to the present invention.
11-05-2019
31
[0139]
13 is a diagram showing an example of an audio reproduction system using another example of
the speaker device according to the present invention.
[0140]
14 is a diagram showing an example of an audio reproduction system using another example of
the speaker device according to the present invention.
[0141]
15 is a diagram for explaining the example of FIG.
[0142]
16 is a cross-sectional view of the structure of the conventional speaker device.
[0143]
17 is a diagram showing an example of the secondary coil unit of the conventional speaker
apparatus of FIG.
[0144]
Explanation of sign
[0145]
21: first magnetic yoke, 21a: center pole portion, 21b: flange portion, 22: second magnetic yoke
(plate), 23: magnet, 24: drive coil (primary coil), 25: secondary coil DESCRIPTION OF SYMBOLS
26 ... Auxiliary diaphragm, 27 ... Integrated component, 28 ... Auxiliary coil, 29 ... Cone paper as
an example of a main diaphragm, 29e ... Edge, 30 ... Damper, 31 ... Speaker frame, 32 ... Gasket,
33 ... Cap, 34 through hole 35 magnetic guide 37a to 37g and 37i to 37p lead wire pair 38a to
38g and 38i to 38p input terminal GP: magnetic gap
11-05-2019
32

JPH0746688

JPH0213100

JPH065297

JPH0614383

JPH0248084

JPH0386000

JPH0546197

JP2000175291

JPH0423598

JPH027696